AbstractProcessor "ignores" some classes ...

I have a custom annotation at the TYPE level, that I want to process using an AbstractProcessor. Everything works ok in most cases, but I have the following problem :

For historical reasons, I build my project by running one javac ant task per package (at least for the big business ones). Let's say I have packageA (containing ClassA) and packageB (containing ClassB)

packageA is built
ClassA is inspected by my AbstractProcessor, as expected
ClassA has a dependency on ClassB
ClassB is [NOT] inspected by my AbstractProcessor (my problem)
packageB is built
since classB was already compiled, it is not inspected by my AbstractProcessor

Therefore, ClassB is never inspected, and I don't know how to solve this issue ... this compiling package cannot be changed, so I have to find a way to deal with those dependencies :(